The invention relates to a method of manufacturing hollow glass objects, in which the material to be formed is taken in the form of a closed-end tube from the feeder and aspirated or blown into a finish mold. By this method both closed hollow glass objects such as hollow spheres and open hollow glass objects such as bottles may be made.
This method makes it possible to manufacture hollow glass objects without the need for special tools for shaping the gob.
A process is already known (Germany Pat. No. DRP 513,479) in which a tube is formed from the melt and is blown into a mold. In this process, the lower edge of the feeder is held at a prescribed minimum distance from the upper edge of the blow mold during the blowing. The portion of the tube that is located between the top edge of the mold and the feeder and has a very low viscosity is expanded so greatly by the blow that it forms a very thin-walled bubble or bursts. This process has considerable disadvantages, namely:
The end of the strand remaining on the feeder can be reclosed only with difficulty because the cold portions created by the bursting first have to be reheated, and the excessively flared end of the tube has to be brought together, and a uniform distribution of masses approximately symmetrical to the main axis has to be established.
The fragments produced by the bursting interfere with production operations.
The excess glass protruding above the mold has to be removed, resulting in fragments.
The glass that is in the mold has to be blown tight again after the bursting of the tube. Due to the cooling of the glass by contact with the mold, this in only partially possible.
The heating and re-forming of the glass which has greatly cooled at the edges requires much time. The quality that can be achieved in the mouth of the bottle is low.